The nation's top intelligence officials delivered their annual global threat report on Tuesday, outlining a strategic landscape rife with dangers from old geopolitical rivalries and new technology to domestic instability and efforts to undermine democratic institutions.

The heads of the Office of the Director of National Intelligence, the Central Intelligence Agency, National Security Agency, Federal Bureau of Investigation, and Defense Intelligence Agency all testified before lawmakers, offering a candid and sobering assessment of the national security challenges the United States faces.

Below is an outline of the top issues that keep U.S. intelligence officials awake at night.

CYBERSECURITY: 'THE UNITED STATES IS UNDER ATTACK'

Increasingly over recent years, emerging threats in the information and technology space have taken precedence over the threat of terrorism and even weapons of mass destruction.

Director of National Intelligence (DNI) Dan Coats identified the cyber domain as one of his "greatest concerns and top priorities," specifically managing the most serious cyber actors, Russia, China, North Korea and Iran.

"Frankly, the United States is under attack," Coats stated bluntly, saying the current geostrategic period "can best be described as a race for technological superiority."

Russia has already exploited the information space to wage propaganda warfare and interfere in elections in the United States and across Europe. According to Coats and CIA Director Mike Pompeo, after the successful meddling in the 2016 election, the United States can expect to see Russia again attempt to interfere in the upcoming 2018 midterm elections.

"There should be no doubt that Russia perceives its past efforts as successful and views the 2018 U.S. midterm elections as a potential target for Russian influence operations," Coats said. He later noted that all 28 of America's NATO allies have relayed concerns that Russia has already or intends to interfere in their national elections, efforts intended to sow discord and undermine democratic institutions.

The intelligence community, Coats added, expects to see Russia continue to use "propaganda, social media, false-flag personas, sympathetic spokespeople, and other means of influence to try to exacerbate social and political fissures in the United States."

Pompeo underscored U.S. election vulnerabilities, saying the CIA has seen "Russian activities and intentions to have an impact on the next election cycle."

A number of senators took aim at the intelligence agencies and President Donald Trump for failing to address the weaknesses of the election system or properly deter Russian actors from meddling in elections in the future.

Pompeo explained that "we do have some capabilities offensively to raise the cost for those who would dare challenge the United States elections," deferring any further comments on those capabilities to a closed session.

China's capabilities in the information and technology space have raised more long-term threats, particularly as China has adopted an "all of society" approach to the acquisition and deployment of information technology.

For year's the United States has been aware of Chinese corporate espionage, intellectual property theft, and other efforts to gain an economic and technological edge. Far from resolving those issues, lawmakers sounded the alarm warning that China is engaged in a well-funded crash program to outpace its rivals in artificial intelligence and quantum computing.

"Where is our national Manhattan program for AI and quantum computing that will match the Chinese?" Sen. Jack Reed of Rhode Island asked the intelligence chiefs.

Both Republican and Democratic senators pressed the intelligence chiefs to explain what they are doing to prevent technology firms closely tied to the Chinese government, like Huawei and ZTE, from infiltrating U.S. markets and using telecommunications products to spy on American users in the government and private sectors.

Ranking Democratic Senator Mark Warner of Virginia warned that China had adopted an "all of society" approach aimed at gaining access to intellectual property, commercializing surveillance technology, and selling those products to unsuspecting U.S. domestic or government buyers.

The intelligence chiefs assured the senators that they were aware of the threat posed by the Chinese technology sector. "Chinese cyber espionage and cyber attack capabilities will continue to support China's national security and economic priorities," Coats said.

Republican Senators on the intelligence committee Tom Cotton of Arkansas and Marco Rubio of Florida recently introduced legislation to block the government from buying equipment from Chinese tech firms Huawei and ZTE, which are believed to be used for economic and other forms of espionage, though China denies the allegations.

The other advanced cyber actors, North Korea and Iran, also remain top concerns, as both nations use information technology to prepare and carry out cyber attacks against the United States and raise money for illicit purposes.

'DECISION TIME' ON NORTH KOREA GETTING CLOSER

North Korea's nuclear weapons program remains an area of serious concern that intelligence officials say will demand some sort of action sooner than later.

"Decision time is becoming ever-closer in terms of how we respond to this," Coats said of North Korea's nuclear threat.

"Our goal is a peaceful settlement. We are using maximum pressure on North Korea," Coats stated, adding that "we have to face the fact that this is a potentially existential problem for the United States."

Sen. Diane Feinstein of California asked CIA Director Pompeo whether his agency had sussed out how North Korean leaedr Kim Jong-Un would react to a U.S. preventive attack on his country. Pompeo affirmed that the CIA had analyzed that contingency, but would not openly discuss the details. Pompeo further acknowledged that the CIA had assessed "what it would take" to bring North Korea to the negotiating table, but again would not openly discuss details.

TERRORISM AND HOMEGROWN VIOLENT EXTREMISM

Since President Trump took office, the Islamic State terrorist group has faced severe battlefield losses in Iraq and Syria, where it currently controls on 2 percent of the territory it once claimed as part of its caliphate. Tens of thousands of ISIS militants have been killed in the U.S. and allied campaign that has been ongoing for more than three years.

However, according to DNI Coats, the losses ISIS has faced in Iraq and Syria have not entirely diminished the threat posed by the terrorist organization in inspiring and recruiting bad actors to carry out terror attacks on U.S. soil.

"U.S.-based homegrown violent extremists, including inspired and self-radical individuals, represent the primary and most difficult to detect Sunni terrorism threat in the United States," Coats asserted.

He explained that while ISIS has lost its claims to a physical caliphate, the group remains a threat in the region and "will likely focus on regrouping" in the ungoverned spaces in Iraq and Syria, "enhancing its global presence, championing its cause, planning international attacks and encouraging members and sympathizers to attack their home countries."

Coats further warned that al-Qaeda remains a major actor in global terrorism and has taken a "long-term approach" to its strategic objective, attacking the United States homeland and U.S. interests abroad.

NATIONAL DEBT REPRESENTS A 'DIRE THREAT' TO SECURITY

After outlining a series of threats external to the United States, DNI Coats turned to an "internal" threat that continues to grow, the national debt.

Coat said the growing U.S. debt "represents a dire threat to our economic and national security."

The current national debt is just below $20 trillion. The latest two-year bipartisan budget agreement signed by President Donald Trump is expected to balloon the federal deficit, with numerous projections anticipating a nearly $1 trillion federal deficit by the end of the fiscal year, almost double the 2017 rate.

"I'm concerned that our increasing fractious political process, particularly with respect to federal spending, is threatening our ability to properly defend our nation over the short-term and especially in the long-term," Coats warned.

Coats is far from the first national security official to warn of the impact of U.S. fiscal instability. In 2010, then-chairman of the Joint Chiefs of Staff, Adm. Mike Mullen warned that the national debt represented the "greatest" national security threat facing the country. That sentiment has since been echoed by top U.S. diplomatic and military officials, including Defense Secretary James Mattis.

"This situation is unsustainable," Coats told lawmakers, encouraging them to take action as soon as possible, "before a fiscal crisis occurs that truly undermines our ability to ensure our national security."

SECURITY CLEARANCES: 'THE PROCESS IS BROKEN'

Intelligent chiefs were also asked to comment on the latest White House shakeup involving former Trump aide Rob Porter, who was granted an interim security clearance despite being the subject of an investigation into alleged domestic abuse.

FBI Director Wray laid out a timeline, pointing to a number of separate occasions that his agency informed the White House that it was looking into the issue of Porter's alleged domestic abuse.

According to Wray, the FBI submitted a partial report to the White House in March, regarding the investigation into Porter's alleged abuse. In late July, the FBI completed a background investigation. Soon after, the agency received "requests for followup inquiry," which it did and submitted that information in November. Porter's file was administratively closed in January. In early February, the FBI received additional information about Porter and passed that on to the White House.

Wray would not comment on the content of the background investigation, but stated that he is "quite confident that in this particular instance, the FBI followed established protocols."

Sen. Martin Heinrich of New Mexico pressed DNI Coats to explain how a number of Trump officials, like Porter and Jared Kushner, were able to obtain security clearances and access to classified materials despite being flagged by the FBI during the background investigation.

"The process is broken," Coats stated unambiguously. "It needs to be reformed."

Coats defended the appropriate use of interim security clearances, especially when a new administration is trying to fill vacant positions. However, in those cases "the access has to be limited in terms of the kind of information they can be in a position to receive or not receive," the director added.

POLITICIZATION OF THE FBI

As the investigation progresses into possible ties between the Trump campaign and Russian government interference in the 2016 election, the president has repeatedly lashed out at members of the FBI and intelligence community.

Earlier this month, Trump said the FBI and Justice Department "have politicized the sacred investigative process in favor of Democrats and against Republicans." He cited a Republican-authored memo pointing to alleged surveillance abuses targeting a member of the Trump campaign.

Director Wray told lawmakers that he had not seen evidence of bias at the agency and repeated his concerns about the accuracy of the GOP-authored memo, which he encouraged the president not to declassify.

While some have said the president's criticism of the FBI is having a negative impact on morale and recruitment, the agency's director disputed the claims of demoralization among his ranks.

"I like to think our people are pretty sturdy," he said. "And I encourage our folks not to get too hung up on what I consider to be the noise on TV and in social media."